President Donald Trump said he is “encouraged” by ongoing attempts to build support for a more conservative immigration overhaul plan introduced by House Judiciary Committee Chairman Bob Goodlatte, R-Va.

WASHINGTON – President Donald Trump reiterated his support Wednesday for a Republican plan to revamp the nation’s immigration system and threatened to veto any other proposal – just as a bipartisan group of senators said they’re on the verge of releasing an alternative plan.

In a White House statement, Trump urged the Senate to back the proposal, saying it accomplishes his vision for immigration. At the same time, the president rejected any limited approach that deals only with “dreamers” – immigrants who have been in the country illegally since they were children – and border security.

Trump’s full-throated endorsement of legislation unveiled this week by a GOP group led by Senate Judiciary Committee Chairman Charles Grassley, R-Iowa, comes as a group of bipartisan senators worked on a possible solution to the intractable issue that could earn enough support in the closely divided Senate.

Sen. Joe Manchin, D-W.Va., who has been co-hosting the bipartisan talks with Sen. Susan Collins, R-Maine, and about 20 other senators, said that the group should have a proposal ready to introduce by late afternoon.

“We’ll have something and it’ll have quite a few co-sponsors – bipartisan,” he said, declining to share other details.

Even if the group unveils a long-anticipated proposal, there is no guarantee that it will earn a vote on the Senate floor, or the requisite 60 votes needed to advance legislation.

And Trump’s latest warnings might deter members of both parties anxious about debating such an emotionally fraught issue at the start of an election year.

Trump said in his statement that he is “asking all senators, in both parties, to support the Grassley bill and to oppose any legislation that fails to fulfill these four pillars – that includes opposing any short-term ‘Band-Aid’ approach.”

Majority Leader Mitch McConnell, R-Ky., also has backed the GOP plan, and most Republicans appeared to be rallying behind the proposal by Grassley and six other GOP senators Tuesday.

It fulfills Trump’s calls to legalize 1.8 million dreamers, immediately authorizes spending at least $25 billion to bolster defenses along the U.S.-Mexico border, makes changes to family-based legal immigration programs and ends a diversity lottery system used by immigrants from smaller countries.

On a conference call with reporters, senior administration officials said the president had made significant concessions to Senate Democrats. Last fall, Trump terminated the Obama-era Deferred Action for Childhood Arrivals (DACA), which had provided temporary work permits to about 690,000 dreamers. White House officials emphasized that Trump’s plan allows far more dreamers to pursue the path to citizenship.

But they added that the border security provisions and the cuts to legal immigration channels are required to stem illegal immigration, reduce a lengthy backlog in the green card process and reduce immigration levels that, the White House argues, have harmed American workers.

“Democrats say, ‘Less for Americans, more for illegal immigrants,’ ” said one administration official, who like the others on the call spoke on the condition of anonymity to discuss internal White House deliberations. “We went as far as we could in that direction, but any more and the House would never take up the bill and the president would not be able to sign it. It would be a waste of the Senate’s time and a waste of Americans’ time.”

Lawmakers have been negotiating under the premise that the bulk of DACA work permits will begin to expire March 5 – a deadline Trump set last fall aimed at giving Congress time to develop a legislative solution for DACA recipients. But judges in California and New York have issued temporary injunctions, requiring the Trump administration to restart the program.

The Department of Homeland Security has done so and the Justice Department has taken the unusual step of petitioning the Supreme Court to hear the case without it going through the standard appeals process. The high court could announce as early as Friday whether it will do so or kick the matter back to the lower courts, which could mean a longer process until the matter is resolved.

Democrats strongly oppose the Grassley plan.

Senate Minority Leader Charles Schumer, D-N.Y., said the bill unfairly targets family-based immigration and that making such broad changes as part of a plan to legalize fewer than 2 million people “makes no sense.”

Meanwhile, Trump said he is “encouraged” by ongoing attempts to build support for a more conservative immigration overhaul plan introduced by House Judiciary Committee Chairman Bob Goodlatte, R-Va. House GOP leaders planned to spend Wednesday whipping potential support for the bill, which is opposed by Democrats and several Republicans because of its aggressive border security policy and changes to family-based immigration.

In the Senate, McConnell has said that he wants debate on immigration to wrap up by Friday, when Congress is scheduled to leave for a week-long recess. But members of both parties said the debate is likely to continue well beyond this week.

“It’s going to take awhile, this is a complicated thing,” said Sen. Marco Rubio, R-Fla. “Isn’t this what people always want, to have a Senate that works and comes up with ideas and has a debate? This is the way the system was designed.”

Sen. Mike Rounds, R-S.D., who is part of the bipartisan group, said he supports the Grassley plan, but realizes it may not earn sufficient support in the Senate.

“We want to make sure if we’re able to – if we’re not successful in that attempt, to look at other alternatives. We’re just trying to cover all the bases,” he said.

Sen. Robert Menendez, D-N.J., warned that the congressional debate was veering too far from the most urgent concern – legalizing the status of dreamers, many of whom are set to lose legal protections when the Obama-era Deferred Action for Childhood Arrivals program expires next month.

“I’m hearing less and less about dreamers and more and more about spending billions of dollars in taxpayer dollars on building a wall,” Menendez said, adding later that issues not directly related to the fate of dreamers are “political catnip designed to incite fear.”

Even if Trump's proposal fails in the Senate, Republicans hope to use the development to put the onus on Democrats and cast them as the ones who are standing in the way of solving the shutdown, after a series of public polls have shown Trump blamed more than Democrats for the impasse.

While Trump's relationship with much of his base remains strong, two years after his inauguration his ties are fraying with some voters, the kind who voted in droves for Trump in 2016 in key pockets throughout the industrial Midwest and flipped previously Democratic states to him.